On'jtk^:^eich^s bf Ou Lake of' Geneva. 905 



when the waters, ^^el^e at their height, is far betieath what oc- 

 curs in thfl Lake uf Geneva. Another circumBtance. which is 

 peculiar to this) Jake is, that at both the right and left sides of 

 the current which issues fromit^ there ate -very icon sideraible; ex- 

 panses, !^)f water, which have absolut^ely nti mbvement whatever. 

 Suchj'-on ihq side of Faguis, ist ^he 'ditch vvhidi: goes to form 

 the Fosse- Vert, and those which extend to the) iadjaioent. fortifica- 

 tions; and On the side of Eaux-Vives particulacly, such is the 

 whole of the margin of the shore to a considerable distance from 

 the.town ; such is the HarboUr of La Eurterie, and the Wooden 

 Harbour, and such the extensive ditches of the fortifications 

 which surround the town on that side. I do not believe that 

 any of the lakes of Switzerland, or of the higher or lower parts 

 of Italy, presents, at the issuing of its waters^. any thing of a si- 

 milar configuration. :'.: ■■'■: ^■•; h 

 • Andi finally, to come to an explanation of the phenomenon as 

 it occurs at the extremity of the lake, I suppose that, in the cir- 

 cumstances of the atmosphere, which I have already pointed 

 out when rain threatens, or considerable/ barometrical changes 

 rapidly succeed each other, tlie waters of the lake, at some dis- 

 tance from the town, are depressed by a column of air which 

 has become heavier than those around it : at the same time, this 

 presatire raises the 'level of: the neighbouring waters, which it 

 may raise, we shall say, to two inches. But if these waters, in- 

 stead of being at the horizontal level, on the contrary, consist of 

 thbsewhich form the rapid fall of the stream, they will then be 

 subjected to two forces, viz. that of the fall, which is carrying 

 them along, and tliat of the atmospheric column which impels 

 them from their level. Under these circumstances, they will 

 follow the diagonal of the two forces, and in a direction which 

 it is not difficult to determine; and they will thus be more or 

 less elevated 5n; a considerable extent of the current. But they 

 caiinot, bd thus elevated, without the current being at the 

 same time diminisl^d, and the waters retarded in their course, 

 and of course augmented in quantity. And as the waters 

 of the • current are in equilibrium with the stiller waters that 

 surround them, they will swell them up, not truly by run- 

 ning over them, but by forming on all sides interior cur- 



X 2 



